Lightroom CC sets keyboard-typed adjustment values randomly to zero

Often, but not always, when I do adjustments via keyboard, Lightroom sets the value back to zero upon pressing the Enter key. The adjustment will still be registered in the protocol though -- by going back a step with CMD+Z, the value appears the way I initially set it. This occurs most often with Exposure, but also with other adjustment values. There seems to be no pattern, which makes it especially annoying.